1. Field of the Invention
The present invention relates to a refrigeration system of a closed cycle, including: a circulation channel through which a refrigerant circulates; and a dry evaporator incorporated in the circulation channel so as to contact a target heating object.
2. Description of the Prior Art
A refrigeration system of a closed cycle is well known to include a so-called dry evaporator. The refrigeration system is often employed in an interior air conditioner, for example. The evaporation of a refrigerant can be promoted within the dry evaporator under a low pressure, so that atmosphere around the dry evaporator can be cooled down. The refrigerant completely evaporates within the dry evaporator in such an interior air conditioner. The quality of the refrigerant is forced to reach 1.0 within the dry evaporator. Only the refrigerant of gas state is intended to be discharged from the dry evaporator.
A cooling system is in general incorporated in a large-sized computer such as a supercomputer and a main frame. The cooling system is designed to cool a semiconductor device module such as a multichip module (MCM). Acceleration of operating clocks and a higher density of electronic elements are predicted to induce the increased quantity of heat in the semiconductor device module. A higher performance of cooling is expected in the cooling system. It is believed that it becomes difficult for a conventional refrigeration system to reliably restrain an increase in the temperature of the semiconductor device module.
The performance of cooling in the dry evaporator may be considered based on the quantity of heat transfer per unit area, namely, a heat transfer coefficient. A higher heat transfer coefficient serves to reliably prevent the semiconductor device module from an excessive increase in the temperature, even when the semiconductor device module suffers from an extreme generation of heat. Heretofore, no specific proposal has been made to increase the quantity of heat transfer per unit area in the technical field of a refrigeration system of a closed cycle.